The ability to treat most advanced solid tumor malignancies has improved to not appreciable degrees in recent years. This is in part due to the lack of new effective agents. Classic cytotoxic DNA-damaging agents have little curative potential in the treatment of advanced malignancies. More emphasis therefore has been placed on both cancer prevention and the development of therapeutic agents with novel mechanisms of action. An example of the latter is the development of monoterpines as anticancer agents. Perillyl alcohol is a monocyclic monoterpine. Monoterpines are commonly and primarily produced by plants and vegetables, including citrus fruits and food flavoring such as mint. Perillyl alcohol has been shown by multiple laboratories to produce significant tumor regression of both chemically induced and transplantable tumors. We plan to perform a Phase I trial of perillyl alcohol in patients with advanced untreatable malignancies to assess the toxicity and relative pharmacokinetics of a new formulation of perillyl alcohol administered on a continuous four times a day schedule. The maximum tolerated dose (MTD) will be determined by a standard Phase I approach. The patient sample size will be dependent on the number of steps required to reach the MTD, typically 20-25 patients. This study will also examine the effects of perillyl alcohol upon various biological endpoints.